''Hydrophilus piceus'' is a species of

beetle Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...

s in the family

Hydrophilidae Hydrophilidae, also known colloquially as water scavenger beetles, is a family of beetles. Aquatic hydrophilids are notable for their long maxillary palps, which are longer than their antennae. Several of the former subfamilies of Hydrophilidae ...

, the water scavenger beetles. This very large aquatic beetle is found in the Palearctic and is known by the common name great silver water beetle.Karaouzas, I., et al. (2014)
Contribution to knowledge of the distribution of the rare great silver water beetle ''Hydrophilus piceus'' (Linnaeus, 1758) (Coleoptera, Hydrophilidae) in Greece.
''Polish Journal of Entomology'' 83(2) 99–107.

Description

This beetle is among the largest aquatic insects. Adults can reach up to in length and in width. The

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e is up to long. The body of adults is black with a greenish or olive sheen. It has protruding eyes and reddish-black antennae.

Biology

This beetle lives in aquatic environments. In some regions it can be found in lakes and ponds. In

Greece Greece,, or , romanized: ', officially the Hellenic Republic, is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. Greece shares land borders ...

it can be found in

lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') ...

s and

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environmen ...

. It has been found at elevations of up to . In Great Britain it lives in ditches with thick vegetation in marshy areas. The beetle is

omnivorous An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nut ...

but favors plant material. It can live for up to 3 years but most individuals die after breeding during their first year. The larvae feed on freshwater snails of the family

Lymnaeidae Lymnaeidae, common name the pond snails, is a taxonomic family of small to large air-breathing freshwater snails, aquatic pulmonate gastropod mollusks, that belong to the clade Hygrophila. Lymnaeidae is the only family within the superf ...

, drilling holes into the shells to feed on the animals. The grubs can then reach 7 centimeters long before

pupa A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in thei ...

ting in the mud. In the spring, the adult female spins a cocoon, fills it with eggs, and sets it afloat.

Distribution

This beetle is native to the western

Palearctic realm The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa. The realm consists of several bioregions: the Euro-Sib ...

, where it occurs throughout much of

Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago ...

, its distribution extending from

Scandinavia Scandinavia; Sámi languages: /. ( ) is a subregion in Northern Europe, with strong historical, cultural, and linguistic ties between its constituent peoples. In English usage, ''Scandinavia'' most commonly refers to Denmark, Norway, and Swe ...

to the Mediterranean, North Africa, and Russia, and as far east as India and China. Its distribution is not continuous because it has been

extirpated Local extinction, also known as extirpation, refers to a species (or other taxon) of plant or animal that ceases to exist in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinct ...

from some areas; it is considered to be extinct in

Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and the ...

and

Luxembourg Luxembourg ( ; lb, Lëtzebuerg ; french: link=no, Luxembourg; german: link=no, Luxemburg), officially the Grand Duchy of Luxembourg, ; french: link=no, Grand-Duché de Luxembourg ; german: link=no, Großherzogtum Luxemburg is a small lan ...

, for example. It is rare in some regions, being found only in specific and relictual habitat types.

References

External links

''Hydrophilus piceus''.
Fauna Europaea.

Bumblebee.org {{Taxonbar, from=Q941070 Hydrophilinae Beetles described in 1758 Beetles of Europe Palearctic insects Taxa named by Carl Linnaeus